I like the idea (if I understand you right) that the player by placing his city have to choose what resources he will produce in the future. It brings in not only the dilemma, where should I build but also how should I build...
Is there any way to manage the production rate or cost to make 2 resources per hex acceptable?

You could make the citys a normal square and in the center make a hole. That way you can place the city on top of the recors you want and still se the recors in the city.

This way you do not need to make the city in anny strange shape. Unless a square donut shape is strange ^^ The hole in the center just have to be a normal round hole or a smaler squared one. Just remember to make it a litle bigger that the resors symbol on the map.

Atleast that is my ide on how to sold the problem.

You can even make it so that you can upgrade youre city so it will include 2 resorces. But then i think the best shape would be a romb, the tilted normal scuare. A hexagon can be made up by 3 rombs. So it would be easy to place them next to eatchother. They still should have the hole in them.

The last idea is a version of both. Make the citys a seperat hex tile placed ontop of teh game board covering the whole hex. with a whole in it leting the player se what resors his city can use. And having a upgraded city just means you replace the city hex with another with 2 holes in it.

Hope it is to some help, and atleast somwhat what you where looking fore.

I really like the idea of a multiple resource hex, it adds another layer of strategy. i think "E" is slightly better than "D" because its only 4 cuts instead of 5. Another idea is to use a ring to surround the resource or you could put the city token in the center with an arrow pointing to the resource. Visually this is less desirable (i think) but easier to make. Hope this may help.

Another idea is to use a ring to surround the resource or you could put the city token in the center with an arrow pointing to the resource. Visually this is less desirable (i think) but easier to make.

Well the reason why I want to do this is that there is not a large amount of hex on the map (average of 8-10 hex per player). So I cannot let players chose their best spot to place their city since they are going to use all of them. So my solution was that players should select a spot within the hex.

The reason why I was thinking of dropping it to 1 ressource is first for the clarity of the board and second, to reduce the number of resource to check to speed up the process.

I like the idea of having an arrow that points at a ressource located on the side. The only problem I see is that tokens could easily rotate during game play and I might flip the city tokens during the game. So I am not sure if it is really a good solution.